As information media devices, such as computers, become more popular and widely used, the semiconductor industry becomes more important. Semiconductor devices generally operate at high speeds and have large storage capacities and information processing capabilities. In order to achieve these characteristics, semiconductor manufacturing technology has been developed to attempt to improve the degree of integration, reliability, and response velocity.
As semiconductor devices become highly integrated with large capacities, gate oxide layers used in fabricating complimentary metal oxide semiconductor field effect transistor (CMOSFET) devices become thinner.
Silicon oxide (SiO2) has typically been used as a material for the gate oxide layer.
Silicon oxide is often used as the gate oxide layer because it displays good thermal stability and reliability and is easily fabricated.
However, since silicon oxide has a low dielectric constant of about 3.9, gate leakage current often occurs due to the reduction in thickness of the gate oxide layer. The thickness of the silicon oxide layer is generally decreased to allow for semiconductor devices to be highly integrated.
Therefore, the use of a high-k material as a gate insulating layer has recently been considered.
A gate insulating layer made of a high-k material is often used as a metal gate electrode including TaN or TiN. When forming such a metal gate electrode, many residues are typically produced during an etching process. These residues may cause subsequent processes in a semiconductor device to fail.
Furthermore, since a large number of carbon (C) and oxygen (O) radicals are often combined in the metal gate electrode, the mobility of electrons is reduced, thereby degrading the performance of a transistor.
Thus, there exists a need in the art for an improved semiconductor device and fabricating method thereof.